From 76b104fee9162ff99386525ab7da99a2a7cd6bd3 Mon Sep 17 00:00:00 2001
From: Victor Giers <mail@victorgiers.com>
Date: Wed, 22 Apr 2026 13:46:20 +0200
Subject: [PATCH] auto-git:  [change]
 tests/unit/world-background-renderer.test.ts

---
 tests/unit/world-background-renderer.test.ts | 62 +++++++++++++++++++-
 1 file changed, 61 insertions(+), 1 deletion(-)

diff --git a/tests/unit/world-background-renderer.test.ts b/tests/unit/world-background-renderer.test.ts
index 1f4322d3..57d4c3b2 100644
--- a/tests/unit/world-background-renderer.test.ts
+++ b/tests/unit/world-background-renderer.test.ts
@@ -1,5 +1,5 @@
 import { Texture } from "three";
-import { describe, expect, it } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 
 import { createDefaultWorldSettings } from "../../src/document/world-settings";
 import { resolveWorldEnvironmentState } from "../../src/rendering/world-background-renderer";
@@ -49,6 +49,66 @@ describe("resolveWorldEnvironmentState", () => {
     expect(lateTwilight.intensity).toBeCloseTo(0.7);
   });
 
+  it("uses a cached blended environment texture during partial image-image twilight blends", () => {
+    const world = createDefaultWorldSettings();
+    const dayTexture = new Texture();
+    const nightTexture = new Texture();
+    const blendedTexture = new Texture();
+    const environmentBlendTextureResolver = {
+      resolveBlendTexture: vi.fn().mockReturnValue(blendedTexture)
+    };
+    world.background = {
+      mode: "image",
+      assetId: "asset-day-sky",
+      environmentIntensity: 0.45
+    };
+
+    const twilight = resolveWorldEnvironmentState(
+      world.background,
+      dayTexture,
+      {
+        texture: nightTexture,
+        opacity: 0.5,
+        environmentIntensity: 0.85
+      },
+      environmentBlendTextureResolver
+    );
+
+    expect(
+      environmentBlendTextureResolver.resolveBlendTexture
+    ).toHaveBeenCalledWith(dayTexture, nightTexture, 0.5);
+    expect(twilight.texture).toBe(blendedTexture);
+    expect(twilight.intensity).toBeCloseTo(0.65);
+  });
+
+  it("falls back to the existing single-texture environment while a blended bucket is unavailable", () => {
+    const world = createDefaultWorldSettings();
+    const dayTexture = new Texture();
+    const nightTexture = new Texture();
+    const environmentBlendTextureResolver = {
+      resolveBlendTexture: vi.fn().mockReturnValue(null)
+    };
+    world.background = {
+      mode: "image",
+      assetId: "asset-day-sky",
+      environmentIntensity: 0.45
+    };
+
+    const twilight = resolveWorldEnvironmentState(
+      world.background,
+      dayTexture,
+      {
+        texture: nightTexture,
+        opacity: 0.5,
+        environmentIntensity: 0.85
+      },
+      environmentBlendTextureResolver
+    );
+
+    expect(twilight.texture).toBe(dayTexture);
+    expect(twilight.intensity).toBeCloseTo(0.65);
+  });
+
   it("fades the night environment in when the authored day background has no image environment", () => {
     const world = createDefaultWorldSettings();
     const nightTexture = new Texture();